Can I connect the K(R), KG), and K(B) pins directly to the GPIO lines of my MPU to control the backlight color, or do I need current limit resistors and a driver to sink the backlight current? What about when using the NHD-PCB12832A1Zrev2 interface board?

You would need current limiting resistors. As for needing a driver, it depends on your micro's specs (if it can sink the rated current on each GPIO), but most likely you should be fine without a driver.If using the interface board, you will not need to add resistors because they are already present on the board itself.

Ok, Thanks. Now I have a question about voltage levels:1. If I use a 3.3V supply, does the interface board provide regulated voltage levels? (i.e. 3.0V for VDD and the green and blue backlights, and 2.1V for the red backlight)2. Where can I find a schematic of the interface board?

1. Yes, all you need to supply is 3.3V to the interface board.2. I'm sorry but there is no schematic available, however, the board is simply made up of the capacitors needed (as in the wiring diagram on page 4 of the display's datasheet, here: http://www.newhavendisplay.com/specs/NHD-C12832A1Z-FSRGB-FBW-3V.pdf (http://www.newhavendisplay.com/specs/NHD-C12832A1Z-FSRGB-FBW-3V.pdf)), and the current limiting resistors for each color LED. The pinout for the interface board can be seen here:http://www.newhavendisplay.com/specs/NHD-PCB12832A1Zrev2.pdf (http://www.newhavendisplay.com/specs/NHD-PCB12832A1Zrev2.pdf)